Multiwavelength light source with precise frequency spacing using a mode-locked semiconductor laser and an arrayed waveguide grating filter

A multiwavelength light source with precise optical frequency spacing can be created by extracting an individual mode of a semiconductor mode-locked laser using an arrayed waveguide grating filter. The outputs of the light source are locked to wavelength division multiplexing (WDM) optical frequency grids using an optical frequency standard light source. They can be successfully modulated by 5 Gb/s nonreturn-to-zero (NRZ) signals and can be transmitted through 100-km-long optical fiber.